Cutoff machine tripping mechanism



w March 28, 1944. J. R. ROSENLEA ET AL 2,345,072

CUTOFF MACHINE TRIPPING MECHANISM Filed Sept. 2, 1941 3 Sheets-Sheet 1INVENTOR. n/OHN R. ROJE/YLE/iF' 4m;

March 28, 1944. ROSENLEAF ET AL 2,345,072

CUTOFF MACHINE TRIPPING MECHANISM Filed Sept. 2,

1941 3 Sheets-Sheet 2 BY Q March 28, 1944.

.1. R. ROSENLEAF ET AL CUTOFF MACHINE TRIPPING MECHANISM Filed Sept. 2,1941 s Shets-Sheet s I N\ TNTORS. Jim/v A. Pasi/vziifarzd Patented Mar.28, 1944 CUTOFF MACHINE TRIPPING MECHANISM John R. Rosenleaf and EmmettD. Benham, Enterprise, Karla, assignors to The J. B.

Ehrsam & Sons Manufacturing Company,

Enterprise, Kans., a corporation of Kansas Application September 2,1941, Serial No. 409,214

21 Claims.

It is the primary object of the present invention to simplify theconstruction and control of cut-01f machines particularly of the typeprimarily intended for use upon plaster board and the like and in whichit is oftendesirable to cause the machine to sever the work upon onerevolution and to perforate the work upon another revolution. Themachine of the present invention is likewise capable of cutting orperforating the work at intervals which are not even multiples of thecircumference of the knife orbits. A further object of the invention isto provide, in a machine of the character here under consideration andhaving a plurality of knives mounted on a continuously operating rotor,means for automatically preventing damage to the work by contact withthose knives during non-active periods of the machine, while insuringagainst bending of the work under the influence of the knives at thetime of coaction of the knives to cut or perforate the work.

Further objects of the invention will appear as the descriptionproceeds.

To the accomplishment of the above and related objects, my invention maybe embodied in the form illustrated in the accompanying drawings,attention being called to the fact, however, that the drawings areillustrative only, and that change may be made in the specificconstruction illustrated and described, so long as the scope of theappended claims is not violated.

Fig. 1 is an elevation of the machine of the present invention;

Fig. 2 is an elevation taken from the left-hand end of Fig. 1;

Fig. 3 is a section taken substantially on the,

line 3-3 of Fig. 1 and looking-in the direction of the arrows;

Fig. 4 is a fragmental section taken substantially on the line 44 ofFig. 1 and looking in the direction of the arrows; and

Fig. 5 is an elevation, upon an enlarged scale, of the left-hand end ofFig. 1.

Referring more particularly to the drawings, it will be seen that wehave illustrated a machine very similar in many respects to the machinedisclosed in our Patent 2,288,921 issued July 7, 1942; but that, in thepresent disclosure, the transaxially-shiftable rotor carries only oneknife, the fixed-axis rotor is continuously driven, the trip mechanismfor connecting the firstmentioned rotorto be driven is quite different,and the driving train and ,control for the rotorshifting cam isdifieren. Too, in the present disclosure. we have provided awork-supporting cradle, shiftable in accordance with the operation ofthe upper rotor, and finding no counterpart in our said patent.

In Figs. 1 and 5 there will be seen the machine bed H) mounted on feetIt and supporting end frames 12 and I3 in which the ends l4 and I5 oflower rotor 16 are solidly journalled. The rotor 16 carries four knivesl1, l8, I9, and 20, spaced apart on its periphery.

One or more brackets 21 provide support for a countershaft 22 to whichis keyed sprocket 23 driven by chain 24 from sprocket 25 on, forinstance, the spindle 26 of a motor 21. Said countershaft 22 carries apinion 28 meshing with a gear 29 carried on a continuation 30 of the end14 of rotor I6, to provide a solid continuous drive for the rotor I6.

A continuation 3| of the end l5 of the rotor 16 is journalled in asupplemental end frame 32 mounted on the bed l0, and carries a gear 33continuously meshing with a gear 34 of equal pitch diameter mounted on astub shaft 35 journalled in the frame member 32. To one face of the gear34 is secured one member 36 of an "Oldham coupling of well-understoodconstruction, while the mating element 31 of said coupling has securedto its outer face a jaw clutch element 38. The elements 31 and 38 areloosely mounted on a projection 39 of one end 40 of an upper rotor 4|,the end 40 and 42 of said rotor being journalled in suitable bearings inbearing carriages slidably mounted respectively in the end frames 12 and13 in the manner illustrated in Fig. 3.

As is clearly shown in Figs. 1, 3, and 5, the end 40 of rotor 4| isjournalled in a slide plate 43 guided for vertical movement in aguideway 44 formed in the end frame l3, said plate being supported by aspring 45. The opposite end 42 of said rotor is similarly mounted, sothat said rotor is transaxially shiftable toward and away from the rotorl6.

Integral with, or fixedly secured to, the plate 43 is a platform 46,formed to provide two hinge lugs 41, 41, in which is received a pintle48 to which are fixed a pair of yoke arms 49, 49 provided with shoes 50,50. diametrically oppositely received in an annular groove 5| formed ina clutch element "52 fixed on extension .39 and adapted to mate withclutch element 38. At least one of said arms is provided with. anextension 53 with which is associated a coiled spring 54 urging saidyoke arms to swing in a counterclockwise direction; as viewed in Figs. 1and 5, to move said clutch element 52 into cooperative relation with theelement 38; but said element 52 is normally restrained against suchmovement and held in the position illustrated in Figs. 1 and 5 by theengagement of a trip dog 55 with the thickened portion 56 of an annularcam collar 51 integral with or fixed to said element 52.

As is clearly shown in Figs. 1, 3, and 5, the dog 55 is reciprocablymounted in a lug 58 carried on said platform 46, and is held in positionby a finger 59 on a rockshaft 66 journalled in bearings 6|, 6| dependingfrom the platform 46, and carrying a lever 62 with which is associated acoiled spring 63 tending to rotate said lever in a clockwise directionas viewed in Figs. 1 and 5, and thereby holding the dog 55 in itsillustrated position.

It will be obvious that the driving train thus far described willproduce continuous rotation of the rotor i5, and will effect rotation ofthe rotor 4| only when the clutch element 52 is engaged with the clutchelement 33; and that the provision of the Oldham coupling permits thetransmission of movement from the stub shaft 35 to the rotor 4| whetheror not those members are in axial alignment. A single knife 64 iscarried by the rotor 4 I.

In the illustrated positions of the parts, the dog 55 cooperates withthe thickened portion 56 of the cam collar 51 to hold the clutch element52 out of engagement with the element 38. counterclockwise movement ofthe lever 62, however, in opposition to the spring 63, will withdraw thedog 55 to permit the spring 54 to move the element 52 into cooperativerelation with the constantly rotating element 38 to drive the element 52and the rotor 4|. If the lever 62 is now promptly released, the spring63 Will urge the dog 55 into engagement with the peripheral surface ofthe collar 51 of the rotating element 52; and as said element rotates,the thin portion of the collar will come into registry with the dog 55to permit said dog to move upwardly into contact with the left-hand,cammed face of said collar. Thus, as the rotor 4| approaches completionof a revolution, the dog 55, acting on the cammed face 56 of the collar51, will shift the element 52 to the right to disengage said elementfrom the element 33. Preferably, a springpressed brake 55 is associatedwith a projecting portion of the end 42 of the rotor 4| to stop saidrotor promptly upon disengagement of said clutch elements, the brake 65being mounted to partake of the transaxial movement of the rotor4l.

Beyond the supplemental end frame 32, the extension 3| carries abevelled gear 66 meshing with a gear 61 fixed on a shaft 68 journalledin suitable brackets 69 and 16. The shaft 68 carries a sprocket 1!connected, by a chain 12 to drive a double sprocket 13, 14 suitablyjournalled on the machine frame. The chain 12 engages the portion 13 ofthe last-named sprocket; and a control chain 15 hangs loosely on thesprocket portion 14, said chain 15 carrying one or more suitablypositioned trip elements 16. It will be clear from the above that thechain 15 is driven with the continuously rotating rotor 6, and, atpredetermined points in the cycle of the rotor l6, a trip element 16will be caused to engage the lever 62 to swing the same in acounterclockwise direction to withdraw the dog 55 to permit engagementof the clutch element 52 with the element 38, and that thereupon therotor 4| will be turned through one revolution, upon the completion ofwhich the now-released dog 55 will cause disengagement of the element 52from the element 38, and the brake 65 will stop the rotor 4|.

Of course, the chain 15 will be so associated with the sprocket 14 as totrip the clutch mechanism at a time such as to bring the knife 64 intovertically downwardly directed position at a time to cooperate with oneof the knives on the rotor l6. It will be obvious that the chain 15 canbe so designed and proportioned as to cause the knife 64 to cooperatewith any one of the knives 0n the rotor |6 upon each revolution of therotor l6, or to cooperate with successive knives on the rotor l6. Thus,depending upon the selection of a chain 15 of suitable length or withsuitably spaced trip elements 16, the rotor 4| can be caused to make onerevolution for each revolution of the rotor I6, or one revolution foreach one and one-fourth revolutions of the rotor IE, or one revolutionfor each one and one-half revolutions of the rotor l6, or one revolutionfor each one and three-fourths revolutions of the rotor H5, or onerevolution for any other number of revolutions of the rotor I6 in thesame arithmetical progression. Thereby, the machine can be caused to cutmaterial traveling therethrough to any desired length greater than theperiphery of the orbit of the knives on the rotor |6 by any desiredmultiple of one-fourth that length.

It is often desirable, particularly in working upon plaster board, tocause a cut-off machine to perforate the board at stated intervalsbetween severing operations. It is for that reason that the rotor 4| ismounted for transaxial movement relative to the rotor l6, and we haveprovided means for automatically shifting the rotor 4| between thatposition in which the knife 64 will cooperate with one of the knives 0nthe rotor I6 to sever the board and that position in which the knife 64will cooperate with one of the knives on the rotor l5 merely toperforate the board without severing it. Referring, again, to Fig. 3, itwill be seen that the slide plate 43 mounts a roller 11 adjacent itsupper end, and that a cam 18 engages said roller to hold the slide plate43 down against the tendency of the spring 45. It will be obvious ofcourse that the other end 42 of the rotor 4| is journalled in a similarslide plate provided with a similar roller with which cooperates asimilar cam which is carried on the same cam shaft 19 with the cam 18.

On the countershaft 22 is fixed a sprocket which drives, through a chain8|, a sprocket 82 fixed on a tubular shaft 83 suitably journalled in theend frames l3 and 32. Fixed to the shaft 83 is a clutch member 84 verysimilar to the member 52, and similarly provided with a cam collar 85having a thickened portion 86, and with an annular groove 81. Yoke arms88, 88 are mounted upon a suitable rock shaft 89 journalled upon abracket 96 carried by the end frame 32, and said arms are received inthe groove 81. At least one of said arms is formed with an extension 9!with which cooperates a coiled spring 92- urging the yoke arms to swingin a counterclockwise direction. Reciprocably mounted in the bracket 98is a trip dog 93 cooperating with the collar 85 normally to hold theclutch element 84 in the illustrated position. Likewise journalled inthe bracket 95, and in an additional bearing 94-, is a rock shaft 95 towhich is fixed a lever 96 engaging the dog 93, said shaft beingresiliently held, by means of a spring 91, in the illustrated position.A lever 98 fixed, to the shaft 95, is disposed in the, path of tripelements 99 carried by a chain I supported on a double sprocket-NI,

I02 driven, by a chain. |03 from a sprocket I04- on the shaft 68. 1

A clutch element I05 is mounted upon a shaft I06 concentric with theshaft 83. When the lever 96 is tripped, the dog 93 will be withdrawn topermit the clutch element 84 to engage the clutch element I05 to drivethe shaft I06 through a single revolution, upon the completion of which,the dog 93, cooperating with the thickened portion 86 of the cam collar85, will disengage the element 84 from the element I05. A sprocket I01on the shaft I06 is connected by'achain I08 to drive sprocket I09 on thecam shaft I9.

; It is here to be noted that the gear ratio between the pinion 28 andgear 29 is one to two, so that two revolutions of the countershaft :22will produce one revolution of the rotor I6; the gear ratio between the.sprocket 80 and the sprocket 82 is one to two, so that two revolutionsof the countershaft 22 will produce one'revolution of' the tubular shaft83; and the gear ratio betweenthe sprocket I01 and I09 is one .to two,sothattwo revolutions of the countershaft 22 will produce one-halfrevolution .of the cam shaft 19'. Thus, each time the lever 98 istripped, the cam shaft I9 will be turned through. one-halfrevolution.Thus, if the trip elements 99 are so arrangedas to trip the lever 98each time the lever 62 is tripped, the machine will sever the work uponodd revolutions of the rotor 4|, and will perforate the work upon evenrevolutions of the rotor 4|. Alternatively, of course, the stops 99maybe so set on the chain I60 as to cause the machine to perforateanydesired number of times between severing operations, or to sever anydesired number of times between perforating operations.

Because the rotor I6 with its. four knives is continuously rotating, itis desirable to elevate the work normally into a plane outside the orbitof the knives on the rotor I5, so that said knives shall not mutilate orscar the work between the points at which the machine seversor--perforates the work. On the other hand, it is undesirable to holdthe work outside the orbit of the knives on the rotor I6 during severingor perforating operations, because if the work were so supported, theeffect of the knife 64 would be to .bend'th'e work downwardly, betweenthe points of support, and into the orbit of the knives on the rotor I6.Therefore, we have provided a cradle for the work comprising idlerollers H0 and III supported in a frame work II2, and positioned onopposite sides of the vertical plane including the axesof the rotor I6and 4|. Theframe H2, in turn, is supported upona frame comprisinguprights H3 and I I4, an upper cross bar I I5, and alower cross bar II6.A two-part slide II'I is reciprocably mounted between the frame elementsH3 and H4, being held in adjusted position therein between bolts II8 andH9, said bolts being oper-. ,able to adjust the position of the frame II2 with respect to the end 42 of the rotor 4|, Suitably fixed to therotor end 42, and rotatable within the slide 1, is an eccentric ringI20. It will be seen that rotation of the rotor-end 42 and the ring I20will cause reciprocation of the cradle with its rollers. I I0 and III,with respect to the axis of the rotor 4|. The opposite end of the cradleis similarly supported by a frame work- I2I associated with the end 40of the rotor 4|; and legs I22 are secured to element 2 and slidablyengage the uprights of the frame mem-- ber|2.

When the rotor 4| is in the position illustrated,-

trated in Fig. 4, in which the rollers I I0 and III will be at theirminimum distance below the axis of the rotor 4|, and in which position,work supported upon the rollers H0 and III will be disposed outside theorbit of the knives on the rotor I6. .As the rotor 4| is rotated, thecam ring I20 will be, rotated therewith; so that, asthe knife 64approaches a vertically downward position, the frame -I I2 will be moveddownwardlywith respect to the rotor 4|, whereby theupper surfaces of therollers H0 and III will fall below th horizontal plane tangent with theorbit of the knives on the rotor I6, so that it will be unnecessary forthe knife .64 to bend the work downwardly intov engagement with thecooperating knife on the rotor l6; As the knife 64 moves beyond itsvertically downward position, the eccentric ring I20 will begin toelevate the framel I2, and the work will be movedout of the orbit of theknives on the rotor I|6 before the next adjacentknife onsaid rotor comesinto a vertically .upwardiposition.

- It will be obvious that the minimum length of material which can becut with the present machine is determined by the periphery of the orbitof the cutting edge of the knife 64. In prac-, tice, this length isusually 48 inches. Since the rotor I6 is provided with four knives,equally spaced, it will be obvious that the machine is capable ofcutting lengths greater than48 inches by any desired multiple of 12inches.

Because the clutches 38, 52,"and 84, I05 are four-jaw clutches, it ispossible to trip the machine at' any time within one quarter of a-revolution of the desired cutting position, and still get an accuratelypositioned cut, because the rotor 4| or the cam shaft 19 will not startto move until the completion of the quarter revolutio I during which themachine is tripped It is our present belief that the trip mechanismincluding the chain I5 and the lever arm 62 will operate satisfactorilyand with sufficient accuracy, even though the sprocket I4 is mountedupon a fixed axis, while the lever 62 moves somewhat in, a verticaldirection. Of course it will be obviously possible, without invention,to support the double sprocket'I3, I4 from the platform 46, providingany suitable means, such; for instance, as a resiliently biased idlersprocket, to compensate, in the chain I2, for variations in the centerdistance between the shaft 68 and the sprocket I4 resulting upon suchmodification.

We claim as our invention:

1. A cut-off machine comprising a pair of knife-carrying rotors,aplurality of knives carried by one of said rotors, a single knifecarried .by the other of said rotors, and means for driving said rotors,including means for selectively disconnecting said last-named rotor fromsaid driving means and reconnecting the same in timed relation to causesaid single'blade to cooperate with any one of said plurality of blades.

2. A cut-off machine comprising a pair 0 knife-carrying rotors, aplurality of knives carried by one of said rotors, a single knifecarried by the other of said rotors, means for transaxially shifting oneof said rotors,'and means for driving said rotors, including means forselectively disthe eccentric ring 1 I 20 will be in the position illusby the other of said rotors, means for transaxially shifting one of saidrotors, and means for driving said rotors, including means forselectively disconnecting said last-named rotor from said driving meansand reconnecting the same in timed relation to cause said single bladeto cooperate with any one of said plurality of blades, and means forvarying the cycle of said shifting means.

4. In a cut-oil machine, a lower rotor, at least one knife on saidrotor, means for continuously driving said rotor, an upper rotor, atleast one knife on said upper rotor, means for driving said upper rotor,means for varying the center distance between said rotors, a worksupport arranged between said rotors and adapted normally to supportwork out of cooperative relation with said knives, and means dominatedby said center distance varying means for shifting said work supporttoward one of said rotors upon reduction in such center distance.

5. In a cut-off machine, a lower rotor, at least one knife on saidrotor, means for continuously driving said rotor, an upper rotor, atleast one knife on said upper rotor, means for shifting one of saidrotors toward and away from the other of said rotors, a work supportarranged between said rotors and adapted normally to support work out ofcooperative relation with said knives, and eccentric means on said upperrotor supporting said work support for transaxial movement with respectto both of said rotors.

6. In a cut-off machine, a lower rotor, at least one knife on saidrotor, means for continuously driving said rotor, an upper rotor, atleast one knife on said upper rotor, means for shifting one of saidrotors toward and away from the other of said rotors, a cradle formed toprovide a rest over which work may move between said rotors, eccentricmeans associated with said upper rotor and supporting said cradle, saideccentric means being transaxially shiftable with said upper rotor toshift said cradle transaxially with respect to said lower rotor, androtatable with said upper rotor to shift said cradle transaxially withrespect tosaid upper rotor.

7'. In: a cut-off machine, a first" knife-carrying rotor, means forcontinuously driving said rotor, a. second knife-carrying rotor, meansfor inter-- mittently driving said second rotor, a work sup portarranged between said rotors and adapted normally to support work out ofcontact with the knives of both rotors, and automatic means forshifting, said work support, when said second r0.- tor is driven, tobring work supported thereonwithin. the paths of the knives of bothrotors.

8; In a. cut-off machine, a fixed-axis rotor, at least one knife carriedby said rotor, means for continuously driving said rotor, asecond rotor,at least oneknife carried by said second rotor, means- 1" orintermittently driving. saidsecond rotor, means for transaxia'llyshifting saidisecond rotor, a work support arranged between said rotorsand adapted normally to support work outside the path of any knifecarried on said lower rotor, and automatic means for shiftingv said worksupport. when said. second rotor isdriven, intoa position in which worksupported thereon is. disposed within, the pathsof the knives. of both.rotors.

9. In a cut-off machine, a. first rotor, a plurality of knives carriedthereon, means for driving said first rotor;. at second rotor, a, singleknife; carried on said second rotor, a drive train for said. secondrotor including a, single-revolutionclutch, and meansdrivenwith saidfirst-rotor fori tripping said clutch at a predetermined point in the;cycle of said first rotor.

10. In a cut-off machine, a first rotor, a plu-- rality of knivescarried thereon, means for driving said first rotor, at second rotor, asingle knife carried on said second rotor, a drive train for said secondrotor including a single-revolution clutch, and means driven with saidfirst rotor and operable to trip said clutch at any of a plurality ofpredetermined'points in the cycle of said first rotor.

11. In a cut-off machine; a fixed-axis rotor, at least one knife carriedby said rotor, means for continuously driving said rotor, a secondrotor, at least one knife carried by said second rotor, means forintermittently driving said second rotor, means for transaxiallyshifting said second rotor, a Work support arranged between said rotorsand adapted normally to support work outside the path of any knifecarried on said lower rotor, and automatic means for shifting said worksupport, when said second rotor is driven, into a position in which worksupported thereon is disposed within the paths of the knives of bothrotors, said last-named means being alternatively operable to cause saidone blade on said second rotor to coact with any one of said pluralityof blades on said first rotor.

' 12. In a cut-off machine, a first rotor, a plurality of knives carriedthereon, means for driving said first rotor, a second rotor, a singleknife carried on said second rotor, a drive train for saidsecond rotorincluding a single-revolution clutch, means driven with said first rotorfor tripping said clutch periodically, means for mechanically varyingthe center distance between said rotors, including a. rotary element, adrive train for said rotary element includinga second single-revolutionclutch, and means driven with said first rotor for tripping said secondclutch.

13. In a. cut-off machine, a first rotor, a plurality of knives carriedthereon, means for driving said first rotor, a second rotor, a singleknife carried on said second'rotor, a drive train for said second rotorincluding a single-revolution clutch, means driven with said first rotorfor tripping said clutch periodically, means for me-- chanically varyingthe center distance between said rotors, including a rotary element, adrive train for said rotary element including speed reducing mechanismandfurther including a second single-revolution clutch, and means drivenwith. said first rotor for tripping said second clutch.

14. In a cut-off machine, a first rotor, a plu- 1 I rality of knivescarriedthereon, means for driving said first rotor, a second rotor, asingle knife carri'ed' on said second rotor, a drive train for saidsecond rotor including a single-revolution clutch,

means driven with said first rotor for tripping said clutchperiodically, means for mechanicallyvarying the center distance betweensaid rotors including a rotary cam cooperating with one of said rotorsand having one position in which the orbits of the knives on the tworotors intersect and a diametrically-opposite position in which theadjacent points" in such orbits are separated but by' a distance lessthan the thickness of the work being operated upon by the machine, adrive. train for said cam including speed reducing mechanism designed toproduce one-half revolution of said cam during one revolution of saidfirst rotor and further including asecond single-revo-- lution clutch,and means driven with saidv first rotor for tripping. said secondclutcln 15. In a out-01f machine, a first rotor, a plurality of knivescarried thereon, means for driving said first rotor, a second rotor, asingle knife carried on said second rotor, a drive train for said secondrotor including a single-revolution clutch, means driven with said firstrotor for tripping said clutch periodically, means for mechanicallyvarying the center distance between said rotors, including a rotary camcooperating with one of said rotors and having one position in which theorbits of the knives on the two rotors intersect and adiametrically-opposite position in which the adjacent points in suchorbits are separated but by a distance less than the thickness of thework being operated upon by the machine, a drive train for said camincluding speed reducing mechanism designed to produce one-halfrevolution of said cam during one revolution of said first rotor andfurther including a second single-revolution clutch, and means drivenwith said first rotor and operable to trip said second clutch at any ofa plurality of predetermined points in the cycle of said first rotor.

16. In a cut-off machine, a first rotor, a plurality of knives carriedthereon, means for driving said first rotor, a second rotor, a singleknife carried on said second rotor, a drive train for said second rotorincluding a single-revolution clutch, means driven with said first rotorand operable to trip said clutch at any of a plurality of predeterminedpoints in the cycle of said first rotor to cause said one blade on saidsecond rotor to coact with any one of said plurality of blades on saidfirst rotor, means for mechanically varying the center distance betweensaid rotors, including a rotary cam cooperating with one of said rotorsand having one position in which the orbits of the knives on the tworotors intersect and a diametrically opposite position in which theadjacent points in such orbits are separated but by a distance less thanthe thickness of the work being operated upon by the machine, a drivetrain for said cam including speed reducing mechanism designed toproduce one-half revolution of said cam during one revolution of saidfirst rotor and further including a second single-revolution clutch, andmeans driven with said first rotor and operable to trip said secondclutch at any of a plurality of predetermined points in the cycle ofsaid first rotor.

17. In a cut-off machine, a fixed-axis rotor, a plurality of knivescarried on said rotor, means for continuously driving said rotor, asecond rotor, a single knife carried on said second rotor, a drive trainfor said second rotor including a single-revolution clutch, means drivenwith said first rotor and operable to trip said clutch at any of a.plurality of predetermined points in the cycle of said first rotor,means for transaxially shifting said second rotor, including a rotarycam cooperating with said second rotor and having one position in whichthe orbits of the knives on the two rotors intersect and a diametricallyopposite position in which the adjacent points in such orbits areseparated but by a distance less than the thickness of the work beingoperated upon by the machine, a drive train for said cam including asecond single-revolution clutch, and means driven with said first rotorand operable to trip said second clutch at any of a plurality ofpredetermined points in the cycle of said first rotor, a work supportarranged between said rotors and adapted normally to support workoutside the orbit of the knives on said lower rotor, and automatic meansfor shifting said work support, when said first clutch is tripped, intoa position in which Work supported thereon is disposed within the orbitsof the knives on both rotors.

18. A cut-01f machine comprising a pair of knife-carrying rotors, aplurality of knives carried by one of said rotors, a single knifecarried by the other of said rotors, means for cyclically transaxiallyshifting one of said rotors in a predetermined relation to the cycle ofoperation of said other rotor, and means for varying said relation tobring said one knife selectively into coaction with any one of saidplurality of knives.

19. In a cut-off machine, a first knife-carrying rotor, means forcontinuously driving said rotor, a second knife -carrying rotor arrangedin cooperative relation with said first rotor, and means forintermittently driving said second rotor to cause rotation thereof inany desired one of a plurality of phase relations to said second rotor.

20. In a cut-off machine, a first rotor, a plurality of knives carriedthereon, means for continuously driving said first-rotor, a secondrotor, a single knife carried on said second rotor, a driving train forsaid second rotor only, including a single-revolution clutch, and meansdriven in synchronism with said first rotor for tripping said clutch ata predetermined point in the cycle of said first rotor.

21. In a cut-off machine, a first rotor, a plurality of knives carriedthereon, means for driving said first rotor, a second rotor, a singleknife carried on said second rotor, a drive train for said second rotorincluding a single-revolution clutch, and means operable to trip saidclutch at any of a plurality of predetermined points in the cycle ofsaid first rotor.

JOHN R. ROSENLE AF. EMME'IT D. BENI-IAM.

